Process of extracting vanadium

ABSTRACT

To separate vanadium from vanadium-bearing material such as slag heated to a temperature at least 600* C. by forming a volatile hydroxide in contact with water vapor and air, and to separate vanadium oxide by cooling the vanadium-containing gas thus formed.

United States Patent [72] inventor Gordon ll. Chambers 8400 St. MartinsLane, Philadelphia, Pa. 19118 (21 1 Appl. No. 744,809

[22] Filed July 15, 1968 [45] Patented Sept. 21, 1971 [54] PROCESS OFEXTRACTING VANADIUM 6 Claims, 2 Drawing Figs. [52] U.S. Cl. 23/16,23/21, 23/140, 23/202 [51 Int. Cl C22b 59/00, C01 g 31/00 [50] FieldolSearch ..23/16, 19.1, 17, 21, 140

allgemeine chemie, Band 316, 1962, pp. 168- I81.

Millner et al., Nature," Vol. 163, No. 4146, April 16, 1949, pp. 601-602Primary Examiner-Herbert T. Carter Attorney-Jackson, Jackson andChovanes ABSTRACT: To separate vanadium from vanadium-bearing materialsuch as slag heated to a temperature at least 600 C. by forming avolatile hydroxide in contact with water vapor and air, and to separatevanadium oxide by cooling the vanadium-containing gas thus formed.

PATENTED SEPZI 1911 0 o 0 0 o 0 0 \M w 0 OOO OOOOO km Nu NVEN 0R. araandbamgara' BY .04 %@0- A TTORNEYS PROCESS OF EXTRACIING VANADIUMDESCRIPTION OF INVENTION The present invention relates to a process ofextracting vanadium as vanadium hydroxide from a solid vanadium-bearingmaterial such as a slag or similar material.

A purpose of the invention is to heat a solid vanadium-bearing materialsuch as a slag or the like to a temperature above 600 C., desirably inthe range of 600 C. to l,000 C., and most desirably in a range of 700 to900 C. and to pass in contact with the vanadium-bearing material a gascomprising water vapor and oxygen.

A further purpose is to maintain the gas at atmospheric pressure.

A further purpose is to maintain the gas at superatmospheric pressure.

A further purpose is to blow the gas through a bed of vanadium-bearingparticles.

A further purpose is to deposit vanadium oxide from the vanadium-bearinggas by cooling it, suitably to a temperature below 500 C.

A further purpose is to maintain gas in contact with thevanadium-bearing material for a time of at least 1 hour.

A further purpose is to reduce the coloring content of solid titaniummaterial by extracting vanadium as the hydroxide by a gas comprisingwater vapor and oxygen.

A further purpose is to selectively extract vanadium in the presence ofone or more of iron, titanium, silicon, aluminum, calcium, magnesium,chromium, manganese, sodium, potassium, and sulfur by removing thevanadium heated to elevated temperature by a gas containing water vaporand oxygen and then deposit vanadium oxide by cooling the gas.

Further purposes appear in the specification and in the claims.

The drawings illustrate diagrammatically apparatus which may be used tocarry on the process of the invention.

FIG. 1 is a diagrammatic view of a muffle apparatus which may beemployed in the invention.

FIG. 2 is a diagrammatic view of a fluidized bed employed in theinvention.

The invention relates to a process of removing vanadium from certainvanadium-bearing materials such as slags and the like, including alloyscrap, dross, cinder and matte. When removal of vanadium is referred to,it is intended to indicate that at least some of the vanadium is takenout, and not necessarily that all of the vanadium is removed.

One application of the invention is in removing much of the vanadiumwhich contaminates certain titanium-bearing slags, and which isparticularly objectionable where it is intended to produce titaniumpigments for coating applications, in which vanadium may impart anundesirable color.

One of the virtues of the process is that when carried out within aproper temperature range it will normally deposit pure vanadium oxide ina single step. It is, therefore, to be preferred to intricate wetmethods.

In accordance with the invention the vanadium material such as a slag isfirst crushed to a granular or powder form. This has the advantage ofexposing present surface and reduces the reaction time. Experiments bythe present inventor indicate that the particle size is not critical.Successful removal of vanadium by the process of the invention has beenaccomplished using granules through mesh per linear inch (Tylerstandard) and also with fine powder, either loose or compressed intopellets.

The present inventor has discovered that the extraction of vanadium fromheated vanadium-bearing materials is greatly promoted by adding to thegas circulated in contact with the vanadium-bearing material oxygen aswell as water vapor.

There is indirect evidence that the vanadium volatilizes in the form ofthe hydroxide and that this hydroxide decomposes upon cooling to amixture of water vapor and vanadium oxide. The product on the cooledsurface of the exit chamber is the oxide, not the hydroxide.

Without limiting to a particular theory, it appears from the experimentsof the present inventor that vanadium hydroxide of higher valence issubstantially more volatile at a moderate temperature range thanvanadium hydroxide of lower valence. It is thus possible to remove asubstantial proportion of the vanadium present without correspondinglyvolatilizing hydroxides of other materials which are likely to bepresent, such as iron, titanium, silicon, aluminum, calcium, magnesium,chromium, manganese, sodium and potassium. Furthermore, although sulfurwill volatilize, it forms a fixed gas (not readily liquified orsolidified) whereas vanadium will separate from a mixture of water vaporand oxygen as solid vanadium oxide at lower temperatures.

In order to obtain best results in the process of the present invention,the vanadium-bearing materials should be heated to a temperature of atleast 600 C. In order to avoid volatilization of other metals which arelikely to be present in a vanadium-bearing slag or the like, thetemperature of treatment should not go as high as l,300 C. and desirablyshould not be above l,000 C. For best results the vanadium-bearingmaterial from which the vanadium is being volatilized should bemaintained at a temperature of 700 C. to 900 C.

The time of treatment will depend upon the extent of vanadium removaldesired, the physical form of the vanadiumbearing material and thenature of the compound in which the vanadium is present in the material.Substantial vanadium removal from a slag or the like can ordinarily beobtained in 1 hour and often 4 hours exposure to the gas is sufficientto 'remove a considerable part of the vanadium. Also, recirculation ofthe gas over or through the vanadium-bearing material is preferred andmuch more prolonged treatment can be used if required.

One unique feature of the present invention is that it removes vanadiumfrom vanadium-bearing titanium and iron slags and the like at moderatetreatment temperatures without the need to fuse and dissolve thematerial for the vanadium extraction.

Following the contact operation by which the mixture of water vapor andair becomes charged with volatile vanadium compound, it is very easy toprecipitate commercially pure vanadium oxide by simply cooling the gassuitably to a temperature below 600 C., preferably below 500 C., andpermissibly to any desired lower temperature.

As previously mentioned, it is believed that a high valence vanadiumhydroxide volatilizes but this form of vanadium is unstable at lowertemperatures and appears to decompose to water vapor and solid vanadiumoxide.

The process may be carried out in a laboratory transpiration apparatusof the character described by G. R. Belton nd F. D. Richardson, 58Transactions of the Faraday Society 1562" (1962). In this apparatus analumina reaction tube is used, conveniently with an inside diameter of0.5 cm. The vanadium-bearing material is conveniently placed 'in arefractory boat of approximately 5 cm. length and inserted in the tube.As an alternative a stainless'steel autoclave may be used instead of thealumina reaction tube.

FIG. 1 illustrates diagrammatically a device of this general characterhaving an autoclave 20 containing vanadium material at 21 and heated tothe desired temperature, conveniently by electric heating means 22. Anoxygen-bearing gas is circulated by a pump 23 through a wash bottle 24containing water 25 held at a suitable temperature, say C., by aconstant temperature bath 26. Thus the gas, suitably air, becomessaturated with water vapor at this temperature and is introduced througha tube 27 and passes over the vanadiumbearing material at elevatedtemperature. From the autoclave 20 the gas passes by a tube 28 to acondenser 30 which is suitably cooled or heated by means 31 to lower thegas temperature to below 600 C. and preferably below 500 C. As aconsequence, vanadium oxide deposits at 32. The gas is then recirculatedthrough a tube 33, there being a discharge connection 34 controlled by avalve 35 to release air and water vapor and there being an inletconnection 36 controlled by a valve 37 to introduce fresh air or oxygenwhen desired. Thus in the apparatus of FIG. 1 the gas containing oxygenand water vapor recirculates repeatedly in contact with the vanadiumbearing material 21 and removes vanadium and deposits it as vanadiumoxide at 32.

F [b 2 illustrates a modified device which can be employed in theinvention. A retort 38 containing a fluidized bed 40 in heated to thereaction temperature by a suitable heating means 41. In this case a gascontaining a mixture of oxygen and water vapor is obtained as previouslydescribed, passes from below through the fluidized bed 40 and isintroduced into a vertical condenser heated or cooled by means 31 anddischarging vanadium oxide 32 at 42. the gas being recirculated as abovedescribed.

It will be evident that recirculation of the gas conserves heat andavoids loss of vanadium, oxygen and water Also, a higher concentrationof water vapor can be employed in the recirculatin g stream if desired.

The literature contains several references to the enhanced volatility ofcertain metals in the presence of water vapor at elevated temperatures.However, there appears to be nothing in the literature to describe thevolatilization of vanadium hydroxide from solid vanadium-bearingmaterials such as glassy slags. Belton and Richardson, A volatile lronHydroxide, 58 2 5 Transactions of the Faraday Society 1562-1572 (1962)described the enhanced volatility of iron at elevated temperatures in agas stream containing water vapor and hydrogen and ascribe thisvolatility of the gaseous compound Fe(OH Belton and Jordan, The GaseousHydroxides of Cobalt and Nickel, 7l Journal of Physical Chemistry 41 14(I967), measured the volatility of cobalt and nickel in mixtures ofwater vapor, hydrogen and argon. These experiments were made withsamples of pure iron wire, nickel wire and cobalt wire. In

these cases a reducing atmosphere was necessary in order to 35volatilize the hydroxides of these metals.

Vanadium has an enhanced volatility in the presence of a high watervapor pressure like these iron group elements, but contrary to thebehavior of these iron group elements. it has above atmosphericpiessurespeetls up the reaction probably because it brings more water vapor intocontact with the vanadium. The process thus can be more effectivelycarried out at pressure of several atmospheres or more.

The temperatures of the vanadiumbearing material is not critical so longas it is above 600 C and preferably above 700 C. at atmosphericpressure. it will be evident that lower temperatures can be used withhigher vapor pressures. The flow rate of the gas over thevanadium-containing material is 0 not important. In some of the testsflow rates of 300 ml. and l liter per minute were used but in othertests the flow rates varied widely without serious effect on theresults.

Tests were carried out over a temperature range of 500 to l,300 C. Thebest results were obtained when the temperature of the vanadium-bearingmaterial was in the range between 700ai 1 i 900 C At both the arid lowerlimits of 500 to l,300 C., the reaction rate slowed down. and at thehigher range the hydroxides of other elements became volatile andappeared to contaminate the vanadium oxide.

Various gases were used in the test program. Among those tried wereoxygen plus water vapor. air plus water vapor. hydrogen plus nitrogenplus water vapor. and air plus oxygen plus water vaporv The best resultswere obtained using air plus water vapor or a synthetic mixture ofnitrogen plus oxygen enriched beyond the ratio present in air, pluswater vapor.

Test periods ranged from I hour to 4 hours and it is evident that longerperiods can be used if desired.

Comparisons were made with gases having no water vapor,

30 gases saturated with water vapor at 80, 90. 95 C. at atmosphericpressure and gases saturated with water vapor at superatmosphericpressures.

Vanadium is present in recoverable quantities in titanium minerals andmagnetites and apatites from many parts of the world, and in slags andthe like derived therefrom. Vanadium is recovered on a commercial scalefrom such minerals at present but the processes are complicated andcostly. Vanadium has a substantial market at relatively high prices andthere been found by the present inventor that the volatility of 40 is adistinct advantage m the present process of direct vanadium hydroxideoccurs at lower temperature and vanadium hydroxide is more volatile inthe presence of an oxidizing atmosphere.

Vanadium appears to be similar to molybdenum in the volatility of thehydroxides in mixtures of water vapor and oxygen at temperature of 600to l,000 C. The behavior of molybdenum is described by Belton andJordan, The volatilization of Molybdenum in the Presence of Water Vapor,68 Journal of Physical Chemistry 2065 (1965) Fortunately. vanadium andmolybdenum rarely occur in he same raw material so that vanadium can beextracted from most materials as pure vanadium oxide withoutcontamination with molybdenum.

The experiments of the present invention indicate that there is a linearrelationship between the percentage of water vapor recovery of vanadiumat high purity One of the distinct virtues of the invention is thatvanadium is a powerful and objectionable colorant in white titaniumdioxide pigments and in titanium dioxide used as an opacifier in ceramicglasses, glasses and enamels It is very difficult to remove vanadiumfrom titanium slags and the like which are to be used .to producetitanium dioxide pigments and opacifiers. it is therefore evident thatthe invention may be employed to reduce the cost of obtaining titaniumdioxide in white form and make available additional raw materials.

The following table shows typical analyses for several vanadium-bearingtitanium-iron raw materials it is decidedly preferable in the presentinvention to employ the slags as raw materials, since high vanadiumrecovery is obtained more reliably and with less difficulty and delayQuebec Ilmenlte- African Canadian hermatlto Australian Finland vanadiumtitanium mineral. rutile, Ilmoutlet slag, percent slag, percent percentpercent pcrcen t 23. 50 0. 67 0. 27 O. 70 0. 3O 12. 00 0 g 37 13 44. 30

0. 23 0. J 4.8. 3.l 0.16 O. l 0 18 0.10 0 l6 0.07 0.06 0.30 0.03 0.02

EXAMPLE 1 in contact with the vanadium-bearing material and the amountof vanadium volatilized in a given time at a given temperature andpressure. Furthermore, increase of the vapor pressure Canadian titaniumslag (Quebec) of the type listed in the table containing 0.57 percent V0 was heatedfor 2 hours in a muffleas in FIG. 1 at 745 C. A stream ofair was circulated over it. the air having been saturated with watervapor in a vessel maintained at 95 C After the test the analysis showedthat the vanadium content of the slag had been reduced to 0.25

percent V,O or 56.4 percent of the vanadium had been extracted.

EXAMPLE 2 The procedure of example I was carried out heating thevanadium slag to 900 C. At atmospheric pressure 60 percent of thevanadium was extracted under these conditions.

EXAMPLE 3 The procedure of example I was carried out using a gasconsisting of percent hydrogen, 90 percent nitrogen, saturated withwater vapor at 95 C. In this reducing atmosphere only 37 percent of thevanadium was extracted instead of 56.4 percent in example I.

EXAMPLE 4 The procedure of example 1 was repeated using a gas mixtureconsisting of pure oxygen saturated with water vapor at 95 C. Thevanadium extraction was only slightly better than that of example 1.

EXAMPLE 5 A series of experiments were carried out in which the vanadiumslag was heated in a stainless steel autoclave and the gas wasmaintained at various pressures in the superatmospheric pressure range.Despite inability to circulate the gas freely around thevanadium-bearing slag, the quantity of vanadium extracted was increasedby about 30 percent over that extracted at atmospheric pressure. Thesetests gave indirect evidence that the vanadium extraction can beincreased to the order of 75 to 80 percent in comparison with 56 percentto 60 percent at atmospheric pressure when using apparatus which moreeffectively provides contact with the vanadiumbearing material.

in view of my invention and disclosure. variations and modifications tomeet individual whim or particular need, particularly in the choice ofraw material, will doubtless become evident to others skilled in the artto obtain all or part of the benefits of my invention without copyingthe process shown, and I, therefore, claim all such insofar as they fallwithin the reasonable spirit and scope of my claims.

Having thus described my invention what I claim as new and desire tosecure by Letters Patent is: i

l. The selective method of extracting vanadium from a complex solidvanadium-bearing mineral and slags derived therefrom containing one ormore of titanium, chromium. and iron, which consists of reducing themineral to articles through 10 mesh per linear inch, maintaining themineral at a temperature of 600 to l,300 C. in contact with a ascomprising water vapor and oxygen until the gas picks up vanadiumhydroxide, removing the vanadium-bearing gas from the vanadium mineraland cooling the gas to a temperature below 600C. to deposit vanadiumoxide selectively to oxides of titanium, chromium or iron.

2. The process of claim 1, which comprises maintaining the gas atatmospheric pressure.

3. The process of claim 1, which comprises maintaining the: gas atsuperatmospheric pressure.

4. The process of claim 1, which comprises passing the gas in contactwith the vanadium-bearing mineral by blowing the gas through a bed ofvanadium-bearing mineral particles.

5. The process of claim 1, in which the temperature of the gas isbetween 600 and l,000 C.

6. The process of removing at least some of the vanadium present insolid titanium mineral or slags derived therefrom, and thereby reducingthe tendency of vanadium to discolor the mineral, which comprisesreducing the mineral to particles through 10 per linear per linear inch,flowing in contact with the mineral a gas comprising water vapor andoxygen while maintaining the mineral at a temperature of at least 600 C.and below 1,300 C., removing the vanadium-bearing gas from the titaniummineral, and then cooling the gas below 600 C. to separate the vanadium.

UNITED STATES PATENT OFFICE CERTIFICATE OF CQRRECTION Patent No. U-S-3,6O7:OO5 Dated fi 97 Inventor) Gordon H. Chambers It is certified that.error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown bolow:

P J 1 Column 1, line 60, the word "present" should be --more--.

Column 3, line 7, the last word in the line should be -is-- instead ofh'm".

Column 3 line 25, the word "volatile" should be capitalized --Volatile.

Column 3, line 41, the word --a should be inserted before the word"lower".

Column 3, line L6, the word "tolmoesacursshould be --temperatures--'.

Column 4, line 4-, the word "pressure" should be -pI*ossur-es-- Column6, line 13, the word "ar tlclos" should no par'ticles Column 6, line 15,the word "as should has ---gas----.

Column 6, line 3 5-, thewords "perlinoar" appear twice and oneduplication should he omitted and the word --mesh-- should be insertedaftor the numeral "10".

Signed sealed this 25th day of April l9??- 3* (Sn-AL Attost:

m'W'AnD JiJ LETCmflLJR. ROBERT GOTTSCHALK Attesting Officer Commissionerof Patents

2. The process of claim 1, which comprises maintaining the gas atatmospheric pressure.
 3. The process of claim 1, which comprisesmaintaining the gas at superatmospheric pressure.
 4. The process ofclaim 1, which comprises passing the gas in contact with thevanadium-bearing mineral by blowing the gas through a bed ofvanadium-bearing mineral particles.
 5. The process of claim 1, in whichthe temperature of the gas is between 600* and 1,000* C.
 6. The processof removing at least some of the vanadium present in solid titaniummineral or slags derived therefrom, and thereby reducing the tendency ofvanadium to discolor the mineral, which comprises reducing the mineralto particles through 10 per linear per linear inch, flowing in contactwith the mineral a gas comprising water vapor and oxygen whilemaintaining the mineral at a temperature of at least 600* C. and below1,300* C., removing the vanadium-bearing gas from the titanium mineral,and then cooling the gas below 600* C. to separate the vanadium.